Summary of this research results is listed below.1.We have established a co-culture system with ovine mature adipocytes and preadipocytes and the data from their experiments indicate that mature adipocytes regulate proliferation and differentiation of preadipocytes.2.Ovine adipocytes actively synthesis and secrete many members of the cytoldne family, such as leputin and TNF-α. They act as inhibitory factor in proliferation and differentiation of mature adipocytes and preadipocytes, and the synthesis and secretion of them are regulated by insulin and IGF-I.3.Our studies demonstrated that the activation of MAP kinase and PI3-kinase contributes to the proliferation and differentiation process of ovine preadipocytes, respectively, and the activation of PI3-kinase may be necessary in the activation of a nuclear transcription factor, PPAr-γ.4.Next, we have searched out new genes related to adipogenesis.(1)Adipogenin, a new adipocyte-specific gene, have been identified Since the expression of adipogenin mRNA is up-regulated during adipocyte differentiation, it is indicated that adipogenin may be involved with adipogenesis, as one of the regulatory of the adipose tissue development.(2)GPCR43, G protein-coupled receptor family having short chain fatty acids as their ligand, mRNA is up-regulated during preadipocyte differentiation. The stimulatory effect of propionate in differentiation of preadipocytes due to anti-lipolytic action through GPCR43.